Mechanical Designs of The Central Detector

Jinyu Fu

2006.02.14

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Outline

1. Configuration of the central detector

2. Stainless Steel Tank

3. Preliminary Design of Acrylic Tanks

(outer and Inner)

4. Summary

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Theoretical configuration of central detector

Inner acrylic tank

PMT

Outer acrylic tank

Steel tank

Central detector

Steel tank of the veto detector

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Main features :

• Three layers : - steel tank outmost (304L) - outer acrylic tank - inner acrylic tank • Different liquids filled in each tank;• PMTs uniformly installed inside the outmost

tank;• ～ 100 tons weight in total;• Mounted inside the steel tank of veto detector;• Immersed in water;• Removable with liquids in all tanks

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Construction of the steel tank

O-ring

Diameter: 5 m Height: 5 m Wall thickness: 10 mm Weight: 15 tons Watertight: necessary

Lifting eyes

Bolted flange jointAccess ports on the openable top cover

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Detector installation

adjustable for orientation

turnbuckle

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Another option for installation meansby mating-conical surfaces

Conical surfaces

Advantage: to be easy mated and oriented

Possible problem: mating-surfaces damaged by over load during assembly

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Finite Element Analysis for steel tank

Load condition: tank structure filled with liquidsConstraint condition: bottom annular surface was constrained

The max. stress: 108 MPaThe max. deformation: 2.8 mm

Unit:Pa Unit:mStress result Deformation result

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Preliminary Design of acrylic tanks － Structure and analysis

•　 Two homocentric acrylic tanks mounted inside the steel tank• Both immersed in liquids• Each of them filled with liquids •　 Quite similar structures•　 The same loads cases• Different dimensions • Ports(pipes) are needed as accesses

Main features:

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The outer acrylic tank

Diameter: 4100 mm Height: 4100 mmWall thickness: 10 mm Ribs thickness: 10 mmTop and bottom covers thickness: 15 mmWeight : 1.4 ton

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Analysis and Calculation

Three kinds of load conditions are considered:

1). Gravity only - to check the intensity when it is empty after fabrication.

2). Immersed (suspended) in liquids entirely - both the inside and outside of the tank are pressed by the different liquids, even the liquids in the same levels the different densities of the them also cause this pressure.

3). Differential pressure loads caused by the liquids levels - only happen when we can’t fill the tanks with different liquids inside and outside at the same level simultaneously.

Just static loads analysis (seismic impact and other shock loads were not considered)

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FEA Calculation result

1) Only under gravity

The max. stress: ～ 2.7MPa

The max. deformation: 1 mm

Unit:Pa Unit:mStress result Deformation result

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2) Entirely immersed (suspended) in the liquids

The max. stress: ～　 3.9 MPa

The max. deformation: ～ 6.2 mm

Acrylic net density: 1.19-0.85=0.34 t/m3

Given density differential: 0.05 t/m3

The loads in proportion as deepness of the liquid.

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3). Differential pressure loads caused by the different liquids levels

Given differential pressure: Caused by 100mm deep liquids with density of 850kg/m3

(the density deferential of inside and outside liquids was ignored)The max. stress: 3.1 MPa

The max. deformation: 2.5 mm

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The inner acrylic tank

Diameter: 3200 mm

Height: 3200 mm

Wall (ribs)thickness: 10 mm

Top and bottom covers thickness: 15 mm

Weight: 0.9 ton

Three loads cases, quite similar with the outer acrylic tank .

There should be better simulated result according to it’s smaller size and higher location. So no need to check it again.

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All the calculation results verified : -the given acrylic tanks structures are reasonable; -adding ribs can well control the deformation and stress and also strengthen the rigidity and intensity without thicker wall

Further given detector configuration : (According to the acrylic tanks structures)

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Summary1) The steel tank:• Basic structure design was proved reasonable with FEA;• Specific design with more accessorial structures will be considered further;• It could be feasible to manufacture after engineering design done:

2) The acrylic tanks: • Basic structure design are roughly simulated with FEA; • FEA results could help us know how to optimize the design models;

• It is necessary to study structure design further: - to control the deformation as minimum as possible with reasonable wall thickness; - to keep the acrylic tanks fixed inside the steel tank; - to ensure safety for tank structure in different load conditions; - to study acrylic materials properties by testing the typical samples; - to make sure manufacture procedures could be realized and meet our design requirements.